1. Field of the Invention
This invention relates to a centrifugal separator with rotor identification mark detection.
2. Description of the Prior Art
A centrifugal separator having a rotor identifying sensor for identifying the rotor with identification marks on the rotor is known. The rotor identifying sensor detects the pattern of the identification marks during accelerating the rotor to generate an identification signal including the identification data of the rotor. Though this identifying sensor can detect the identification marks, the rotor identifying sensor may fail to detect the identification marks because vibrations occur in the rotor during acceleration due to rotor setting conditions or unbalanced conditions of samples.
Another type of rotor identifying sensor is disclosed in Japanese patent application provisional publication No. 6-198219. In this rotor identification sensor, on the bottom of a rotor, a plurality of magnetic positions, that are equi-angular around the axis of the rotor, are predetermined. The pattern of present or absent magnets provides the identification data. Though this rotor identification sensor can detect the identification data irrespective of rotation and stopping, a plurality of sensor elements are required.
Still another type of rotor identifying sensor is disclosed in Japanese patent application provisional publication No. 10-34021.
FIG. 3 is a block diagram of this prior art centrifugal separator and FIG. 4 is a bottom view of the rotor used in this prior art centrifugal separator. The rotor 201 has a rotor identification adopter 202 mounted on the bottom of the rotor 202. The rotor identification adopter 202 has holes and flat surface portions as identification marks 203 at equiangular arranging positions along a circle on the bottom surface of the rotator identification adopter 202. The hatched circles in the drawing represents the holes and the circles without hatching represents the flat surface portions. The centrifugal separator further includes a sensor 204 to generate a detection signal indicating the detected holes and flat portions. The variation of the detection signal provided with rotation of the rotor 201 represents the pattern of the holes and the flat portions at the equiangular arrange positions. The variation of the detection signal provides the binary code with reference to a rotary position signal from a rotary encoder 211.
The rotor 201 is rotated by a motor 210. The detection signal from the sensor 204 and the rotary position signal from the rotary encoder 211 are supplied to a processing circuit 212 to be processed.
In the above-mentioned prior art centrifugal separators, it is general to read the identification marks on the rotor at a stabilized rotation speed of the rotor in consideration of vibration of the rotor.
The aim of the present invention is to provide a superior centrifugal separator.
According to the present invention, a first aspect of the present invention provides a centrifugal separator comprising: a motor for rotating one of changeable rotors, each of changeable rotors having an identification mark portion on each of said changeable rotors; driving means for driving said motor; identification mark detection means for detecting said identification mark portion to generate an identification signal; and control means for operating said driving means to start and accelerate rotation of said motor, detecting whether said identification signal is detected during acceleration of said rotor, detecting whether said identification signal has been detected before said motor reaches a predetermined rotation speed, and controlling said driver to rotate said motor at a steady state rotation speed (stabilized rotation speed) if identification signal has not been detected before rotation of said motor reaches a predetermined rotation speed, to provide detection of said identification mark portion by said identification mark detection means.
According to the present invention, a second aspect of the present invention provides a centrifugal separator based on the first aspect, wherein said control means cyclically detects whether said identification signal is detected during rotating said rotor at said steady state rotation speed, informing the user of an error when said control means fails to detect said identification signal a predetermined times.
According to the present invention, a third aspect of the present invention provides a centrifugal separator based on the first aspect, wherein said control means cyclically detects whether said identification signal is detected during rotating said rotor at said steady state rotation speed, informing the user of an error when said control means fails to detect said identification signal within a predetermined interval.